Portable electron beam welding apparatus

ABSTRACT

An electron beam welding unit is described which enables an operator to directly manipulate the orientation of the electron gun forming the welding beam in order to control the location on a workpiece at which the beam impinges. To this end, the electron gun is mounted within a vacuum chamber on a first portion of its wall which can be moved with respect to the remainder of the vacuum chamber wall. Such first wall portion of the chamber is connected to the remainder of the chamber wall by a flexible bellows which permits the desired movement of the first wall portion while yet assuring integrity of the vacuum within the chamber. A handle for grasping by the operator is provided on the exterior surface of the first wall portion so that the operator can move the wall and, hence, move the electron gun to change the path of its beam. The electron gun of the unit is in the form of a cartridge which is easily removable for replacement and is provided with a structurally stable electron generating filament. The unit further includes a high voltage power supply which is quite compact and assures low current ripple. The power supply and a full vacuum system for the unit, including an unique valve arrangement, are all housed together with the remainder of the unit to provide a small, portable unit.

e 25da 1OR United States Patent [191 McFarland et a1.

[451 Sept. 25, 1973 PORTABLE ELECTRON BEAM WELDING APPARATUS [22] Filed:May 20, 1971 [21] Appl. No.: 137,568

[52] US. Cl. 219/121 EB [51] Int. Cl B73k 15/00 [58] Field of Search219/121, 121 EB, 219/121 EM, 72, 74; 250/495 A, 49.5 R, 49.5 TE;137/630.l9

[5 6] References Cited UNITED STATES PATENTS 2,404,157 7/1946 Ahalt219/74 2,459,812 1/1949 Griffiths 219/74 3,136,883 6/1964 Radtke 219/121EB 3,424,891 l/l969 Anderson et a1. 219/121 EB 3,418,526 12/1968 Simonet a1 219/121 EBX 3,235,727 2/1966 Shapiro 250/49.5 3,219,792 11/1965Pederson 219/121 EM X 3,283,120 11/1966 Spruck 219/121 EB 3,243,5703/1966 Boring 219/121 EB 623,909 4/1899 Kaeferle l37/630.19 X

Primary Examiner-J. V. Truhe Assistant Examiner -Gale R. PetersonAttorney-C. Michael Zimmerman [5 7] ABSTRACT An electron beam weldingunit is described which enables an operator to directly manipulate theorientation of the electron gun forming the welding beam in order tocontrol the location on a workpiece at which the beam impinges. To thisend, the electron gun is mounted within a vacuum chamber on a firstportion of its wall which can be moved with respect to the remainder ofthe vacuum chamber wall. Such first wall portion of the chamber isconnected to the remainder of the chamber wall by a flexible bellowswhich permits the desired movement of the first wall portion while yetassuring integrity of the vacuum within the chamber. A handle forgrasping by the operator is provided on the exterior surface of thefirst wall portion so that the operator can move the wall and, hence,move the electron gun to change the path of its beam. The electron gunof the unit is in the form of a cartridge which is easily removable forreplacement and is provided with a structurally stable electrongenerating filament. The unit further includes a high voltage powersupply which is quite compact and assures low current ripple. The powersupply and a full vacuum system for the unit, including an unique valvearrangement, are all housed together with the remainder of the unit toprovide a small, portable unit.

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\ 5O Sieoqge @.9Tliarland BY lifford Zifieoder ATTORNEY PORTABLEELECTRON BEAM WELDING APPARATUS I BACKGROUND OF THE INVENTION Thepresent invention relates to apparatus for directing impingement of abeam of radiation onto an object and, more particularly, to such anapparatus which is compact and portable and is especially adapted forelectron beam welding and the like.

Electron bombardment is now commonly used as a heat source for precisionwelding, brazing, or annealing parts made of various materials. Thebombardment is obtained by generating an electron beam and directing thesame onto the part or workpiece to be heated. It is generally necessaryto change the location at which the beam impinges on the object beingirradiated. For example, in welding, it is necessary to continually movethe point of impingement along the joint of the two pieces to be joinedin order to provide the desired heating in an even manner along the fulljoint.

The electron bombardment must take place within an evacuatedenvironment, e.g., at a pressure of torr. Because of this, the formationof the electron beam and the bombardment generally take place within avacuum chamber. It will be appreciated that the vacuum chamber willgenerally prevent the operator from directly moving during an operationeither the electron gun for generating the beam or the workpiece inorder to change the point of impingement of the beam on the workpiece.For this reason, various mechanisms have been provided to enable theoperator to control the movement from outside the chamber. For example,in some electron beam generating devices the electron gun for generatingthe beam is mounted on tracks or the like to permit it to be movedwithin the chamber. In others, it is the support for the workpiece whichis mounted on tracks or a similar mechanism to provide the relativemovement between the workpiece and the gun. Because the desired movementof either the gun or workpiece must be controlled from outside theevacuated chamber, various vacumm interlocks and the like have to beprovided through the chamber wall leading to knobs, levers or switchesfor manipulation by the operator. It will be appreciated that thesetypes of controls, though, will not give the operator a good feel forthe movement which he is providing. That is the actuating movements ofturning a knob or flipping a switch, for example, are only indirectlyrelated to the movement which will be caused within the chamber, and theoperator must have considerable experience before he can correlate themovements to provide the precise control that is often necessary inprecision electron beam work.

Existing electron beam generating units for welding and the like haveother disadvantages as well. For example, because of the necessity ofproviding a vacuum system for evacuating the work chamber, as well as apower supply for powering the electron beam generating device, most ofsuch systems are made up of a plurality of separated subsystems. Theresult is that the beam generating units are not portable and all workmust be brought to them, rather than they taken to the work. This hasrestricted the use of electron beam welding and brazing of large,unportable parts. Moreoverfmany available systems lack flexibility and,in general, have a relatively high initial cost and require largemaintenance expenditures.

SUMMARY OF THE INVENTION The present invention is an apparatus fordirecting impingement of a beam of radiation onto an object which isespecially adapted for electron beam welding and the like and whichenables direct manipulation by the operator of the location of the placeof impingement of the electron beam on a workpiece. To this end, theapparatus includes, as is conventional, a chamber for defining anevacuated volume adjoining the portion of an object or workpiece to beirradiated with an electron beam. lf further includes means such as anelectron gun for introducing the desired beam of radiation to thechamber. The wall of the chamber includes at least two portions. A firstone of such wall portions has the beam introducing means mounted thereonor otherwise associated with it for movement therewith. In thisconnection, the means for introducing a beam of radiation into thechamber is most desirably an electron beam gun which is mounted withinthe chamber on the innersurface of the wall first portion.

The remainder of the chamber wall generally defines the evacuatedvolume, and connecting means, e.g., a flexible bellows, secures thefirst portion of the wall to the remainder of the chamber wall in agenerally vacumm tight manner enabling the first wall portion to bemoved or reoriented with respect to the remainder of the wall. A handlefor grasping by an operator is secured to the first wall portionexteriorly of the chamher.

It will be appreciated that with the above arrangement an operatorutilizing the apparatus can directly manipulate the angular orientationof the first wall portion with respect to the remainder thereof bymerely grasping the handle and moving the same as desired. Movement ofthis wall portion will also reorient the beam introduction meansangularly with respect to the remainder of the chamber, and, thus,change the path of the beam through the chamber. In this manner, theoperator can directly manipulate the path of the beam through thechamber and, hence, change the point of impingement of the beam on anobject supported within the chamber, in a natural manner enablingprecise control of the point of impingement. That is, the movement ofthe gun within the chamber closely follows the control movement of theoperator in a manner which should be familiar to the operator and forwhich he should have a good feel since the movements are basicallyrelated to one another.

The apparatus of the invention includes other features and advantageswhich make the same especially useful and desirable for electron beamwelding and the like. For example, it includes means for removablymounting the electron gun within the chamber in a quite simple mannerwhich enables the same to be easily replaced as necessary. In thisconnection, the filament of the gun is provided with an unique supportarrangement assuring its structural integrity at the extended highoperating temperatures to which such a filament is often subjected. Theapparatus of the invention also desirably includes as an integral partof the combination a power supply for the electron gun which is quitecompact and yet assures low current ripple. A vacuum system havinga,valve and valve control arrangement assuring fail-safe operation whileyet being quite simple and compact is also provided as part of theinvention. These and other features and advantages of the invention willbecome apparent and will be described in more detail in the followingdescription of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the accompanyingfour sheets of drawings:

FIG. 1 is an elevation view of a preferred embodiment of the apparatusof the invention;

FIG. 2 is an enlarged broken away perspective view of the gun and workchambers of the embodiment of FIG. 1;

FIG. 3 is an enlarged broken away and partial elevational view of thegun chamber illustrating the manner in which the electron gun ismovable;

FIG. 4 is a partial perspective view illustrating the means of thepreferred embodiment for mounting the electron gun cartridge within thechamber, with such cartridge exploded therefrom;

FIG. 5 is an enlarged cross sectional view illustrating the manner inwhich the electron gun cartridge is removably securable within thechamber;

FIG. 6 is a partial perspective view of the filament of the electron gunof FIGS. 4 and 5 depicting the manner in which it is supported withinthe gun;

FIG. 7 is a block diagram of the power supply for powering the electrongun of the apparatus of the invention;

FIG. 8 is a schematic showing of the vacuum system for the apparatus ofthe invention and the control valve arrangement therefor; and

FIG. 9 is a diagramatic illustrationofa check system for determiningwhether or not various components of the apparatus are functioningcorrectly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS There is shown in FIG.I a preferred embodiment of the invention, generally referred to by thereference numeral 11, which is especially adapted for electron beamwelding, brazing and annealing. The unit 11 includes a generallycylindrical work chamber 12 within which the object or workpiece to beirradiated is supportable, and a generally dome shaped gun chamber 13above the work chamber for housing means for generating an electronbeam.

The work chamber 12 and gun chamber 13 are hermetically secured togetheras shown, and are mounted in a vacuum tight relationship on the upperplaner surface 14 of a cabinet 16. The chambers 12 and 13 and thecabinet surface 14 thus define a hermetically enclosed volume withinwhich an electron beam can be generated and impinge a workpiece to theirradiated. As is illustrated, the gun chamber 13 includes a pair ofopposite viewing ports 17 and 18 for viewing and illuminating,respectively, work in progress within the work chamber. The work chamber12 includes a pair of access ports 19 for providing access to theinterior of the work chamber to enable workpieces to be changed and alsoto allow different support fixtures for the workpiece to be used.

The apparatus 11 is a generally self-contained unit. That is, forreasons which will be described in more detail hereinafter, both thepower supply for the beam generating means and the vacuum system forevacuating the chambers 12 and 13 are sufficiently compact to be housedtogether within the cabinet 16. Such cabinet also includes the othercontrols and circuitry necessary for operation of the system. In thisconnection, display and controls panels 21 and 22 are provided on thecabi net at locations which facilitate access by an operator to thesame. The only external means necessary to use the system is anelectrical outlet. Because the unit is generally self-contained andsmall, it can be brought to the location of the work to be done and thusenables electron beam welding to be used at locations away from a normalwelding shop or location.

As a particularly salient feature of the present invention, it includesmeans by which an operator can vary in a quite simple and direct mannerthe location on a workpiece at which the beam of radiation impinges.Reference is made to FIGS. 2 and 3 which show such means in detail. Theobject to be irradiated is diagramatically shown as a workpiece 23mounted on a support plate 24. It will be appreciated that various typesand shapes of objects can be irradiated, and that the means forsupporting the same within the work chamber 12 can take various formsand could be, for example, a fixture for continuously moving theworkpiece over a prescribed path.

Most desirably, means are provided for applying a positive electricalbias to the support plate 24 for capturing stray electrons within thechamber. That is, a positive dc power supply 25 is connected to theplate through both a meter 30 which provides a visual indication of thetotal number of electrons collected, and an adjustable resistor 35 whichenables the amount of the bias to be simply adjusted.

The means for generating an electron beam is in the form of a gun 26depending downward from a disc shaped mount 27 positioned adjacent theupper portion of the gun chamber 13. As is illustrated, a mounting rod28 extends upwardly from disc 27 and is secured to the inner surface ofa plate 29 which is also discular shaped.

The plate 29 acts, in effect, as a portion of the wall of the chamberdefining the evacuated volume for the irradiation. Moreover, it issecured to the remainder of the chamber wall by connecting means whichenable it to be reoriented with respect to the remainder of the wallwhile maintaining the integrity of the vacuum. In the embodimentillustrated, this connection is obtained via a flexible bellows 31 ofmetal or other material which includes at its opposite ends vacuumsealing flanges 32 and 33, respectively. Flange 32 is suitably securedin a vacuum type manner to the plate 29, such as by bolts 34, and theflange 33 is secured to a mating vacuum flange 36 at the upper end ofchamber 13.

The bellows 31 acts, in effect, as a second wall portion of the chamberwhich is flexible and connects the plate 29 or first wall portion to theremainder of the chamber wall. It will be recognized, though, that therelative movement between the wall portion 29 and the remainder of thechamber wall could be obtained in other manners. For example, the wallportion 29 could be in the form of a ball which is rotatably mountedwithin a socket in the wall 13 and to which is secured the gun 26.

The gun mount 27 is rigidly secured to the rod 28 which is, in turn,rigidly secured to the interior surface of plate 29. The result is thatthe gun mounting arrangement and, hence, the electron gun 26 itself, ismounted to the plate 29 for movement therewith. A

handle 37 for grasping by an operator is secured to the plate 29exteriorly of the chamber 13.

It will be appreciated that by reason of the described structure, anoperator of the apparatus can angularly reorient the plate 29 withrespect to the remainder of the wall defining the evacuated volume,simply by manipulating the handle 37. That is, the flexible bellows 31connecting the plate 29 to the gun chamber 13 enables the wall 29 to betilted in any direction with respect to the horizontal plane normallydefined thereby. Such tilting will cause a corresponding movement of thegun 26 within the chamber, and thus changed the path of a beam issuingtherefrom to change the location on a workpiece at which the beamimpinges.

It will be appreciated that although the positioning means describedabove for varying the place of impingement of the beam on the workpieceis quite simple, it provides the operator with a good feel of themovement within the chamber he is causing when he manipulates the handle37. That is, the gun 26 is, in effect, directly connected with thehandle 37 so that movement of such handle will cause a correspondingdirect movement of the gun. The result is that the oper ator is able tocontrol the path of the beam on the object being irradiatedwith theprecision which is often necessary to obtain the desired effect.

Locking means are provided for selectively locking the plate 29 in adesired orientation with respect to the remainder of the chamber wall.The locking means will thus hold the electron gun in a selectedorientation to maintain the beam of electrons issuing therefrom on apredetermined path to impinge at a specific desired location. Moreparticularly, a pair of rings 38 and 39 coaxially surround the bellows31 and are gimbally mounted to one another and between the flanges 32and 33 of the bellows. That is, the outer of the two rings, ring 39, issecured for rotation about the axis 41 on a pair of brackets 42 whichextend upwardly from the flange 33, and the inner ring 38 is pivotallysecured to the ring 39 for rotation about an axis 43 which is orthogonalto the axis 41. The ring 38 is also secured to the upper flange 32 ofthe bellows by opposed brackets 44. The resulting structure is agenerally conventional gimbal arrangement which enables the desiredtilting o'r reorientation of the plate 29 with respect to the remainderof the chamber wall, while allowing the plate 29to be locked in apreselected orientation. For this purpose, knobs 46 and 47 are providedfor respectively locking via a friction lock or the like, the rings 39and 39 in a predetermined orientation with respect to another and to theremainder of the structure to hold the plate 29 in a desiredorientation.

As another particularly salient feature of the invention, the electrongun 26 mounted within the chamber in a manner which enables easyreplacement thereof while yet assuring good electrical contact betweenit and the mount. That is, the electron gun 26 is provided in the formofa cartridge which can be plugged into the mounting disc 27. A collar47 depends downwardly from the mounting disc to define therewith asocket for receiving the end portion of the gun, and cooperating meansare provided on the gun end portion and the socket for rigidly securingthe gun within the socket via a mechanical snap fit while enabling thedesired intentional removal of the gun for replacement. Moreparticularly, an indentation in the form of an annular circumferentialgrove 48 is provided on the inner surface of the socket 47. The rear endportion of .the gun is correspondingly provided with a spring metalsleeve 49 which is slotted to provide an annular array of leaf springfingers 51 as is illustrated. Each of such spring fingers 51 is deformedradially outwardly of the gun to provide a convex protuberance 52 shapedto mate with the groove 48. It will be seen that the resulting pluralityof such protuberances will provide a generally annular protuberancearound the sleeve 49 which will mate around the full periphery of thegun with the groove. The result is that good physical contact ismaintained between the gun and the collar not only to assure a tightmechanical connection between the same but also to assure a goodelectrical connection between the two. In this regard, the collar 47 andthe spring fingers 51 act as an electrical grounding path for theelectron gun.

The electron gun cartridge and the socket also include electricalconnectors for providing connection between the electrical elements ofthe gun and the socket when the gun is mechanically secured within suchsocket. That is, a plurality, in this case three, electrical pins 53,extend upwardly for reception within corresponding pin sockets, (notshown) in the base wall of the gun socket. Such pins are suitablyconnected with the various electrical components of the gun to providepower and appropriate biasing thereto. Such components include, as isconventional, a heater filament 54 of-tungston or the like, enclosedwithin a cathode cup 56 for providing a bias for single image focusing,an anode 57 for drawing electrons from the filament 54, and a focusingelectromagnetic lense 58 for forming and focusing the desired electronbeam.

The focusing lense 58 can be made adjustable in order to adjust thefocusing of the beam. The various parts of the gun are secured togetherand maintained in their relationship by conventional parts as shown.

The filament 54 is so designed and supported within the gun 26 that itsstructural integrity is assured at extended high operating temperatures.In this connection, as is best illustrated in FIG. 6, the filamentincludes a generally U-shaped wire portion 59 having a pair of legs 61and 62 which are mounted at their ends at spaced locations to aninsulator support 63 via inwardly projecting ear terminals 64 and 66.The U- shaped portion of the filament further includes a base 67 which,as is conventional, is the source of electrons to be drawn from thefilament by the anode 57. In keeping with the invention, the filament ofthe electron gun includes an additional third leg 68 which extendsbetween the base 67 and a third ear 69 projecting inwardly of thesupport 63. It will be seen that the location at which the third leg issecured to the support by the ear 69 is to the side of the locations atwhich the legs 61 and 62 are secured thereto. This provides the filamentwith a tripod support which assures three dimensional stability of thefilament at all times.

Besides assuring structural integrity of the filament, the leg 68 alsoenhances the emission of electrons from such filament. That is, the endof such leg which is secured to the base 67 of the filament is sosecured thereto by being wrapped therearound. This provides an emittingsurface at such base which is enlarged when compared to the emittingsurface of conventional U- shaped filaments.

It should be noted that further legs could also be added to the filamentto add additional stability thereto. In any event, at least one of thelegs in addition to the legs 61 and 63 normally associated with the U-shaped filament, should be secured to the support at a location which isspaced from the locations at which the legs 61 and 63 are secured toprovide the desired tripod support.

As has been mentioned previously, the power supply for powering thefilament of the electron gun of the invention is quite compact and yetassures that the generated electron beam is quite steady, i.e.,continuously maintains a desired power level. FIG. 7 is a block diagramillustrating the major components of such power supply and how theyinterrelate. Block 71 of the diagram represents an external supply of240 volts alternating current, such as is commonly found on industrialpower supply lines. The power on the line is fed first into an isolationtransformer 72 of the power supply of the invention which protects theremaining components of the power supply from changes which might occurto the external power. The unchanged but current limited voltage fromthe isolation transformer is fed to a rectifier 73 which converts the240 volt alternating current to 300 volt direct current. Such current isfed from the rectifier to a storage capacitor 74.

The 300 volt charge stored on capacitor 74 is fed through a switchingregulator 76 to another storage capacitor which is maintained atnominally 200 volts direct current. As will be explained hereinafter, afeed back arrangement is provided for controlling the switchingregulator to assure that the charge stored on the capacitor 77 issufficient to provide the desired voltage. The capacitor 77 is connecredwith a 1,000 cycle driver 78, the oscillation for which is provided byan oscillator 79. The resulting 1,000 cycle voltage is fed to a step uptransformer 81 which converts the same from 200 volts to 30,000 volts.From such transformer the voltage passes via a rectifier 82 whicheliminates the positive portion of the cycle to deliver to a storagecapacitor 83, a 30,000 volt negative charge. The capacitor 83 isdirectly connected through a series limiting tube (not shown) with thefilament 54 of the electron gun to deliver to it the necessary voltagefor generating electrons.

As mentioned previously, means are provided in the power supply forassuring that the voltage maintained on the storage capacitor 83 ismaintained at a negative 30,000 volts. In this connection, a voltagesensing device 84 is connected with the storage capacitor to determineany voltage changes thereon. Such voltage sensing device can beadjustable as by way of an adjustable resistor schematically illustratedat 86 to enable one to set it for a desired voltage sense. The voltagesensing device 84 reacts to any change in the voltage on the storagecapacitor 83 by driving a switch regulating amplifier 87 which, in turn,drives the switch regulator 76 to assure that the charge fed fromstorage capacitor 74 to capacitor 77 is sufficient to maintain thecapacitor 77 at the required 200 volts level. This will assure that thestorage capacitor 83 is also maintained at the desired 30,000 negativedc. voltage.

The inclusion in th power supply of the l,000 cycle oscillator anddriver for oscillating the voltage assures that a sufficiently steadystate charge is maintained on the storage capacitor 83 to maintain theelectron beam generated by the gun correspondingly steady. That is, theresulting electron beam will be a so-called low ripple" beam. Moreover,the increase of the voltage from the 240 volts provided by the externalsource to 30,000

volts correspondingly reduces the amount of charge which must bemaintained on the capacitor 83. Thus such capacitor can be quite compactand enables the power supply to be housed within the cabinet 16.

The full vacuum system for evacuating the work and gun chambers 12 and13 is also housed within the cabinet 16. As a particularly salientfeature of the instant invention, the vacuum system includes a valvecontrol arrangement which enables the system to be simply controlled byan operator while yet utilizing one mechanical pump for both roughpumping and as a finishing pump for a diffusion pump. The valve controlarrangement also assures failsafe operation of the system. FIG. 8 is aschematic representation of such system as assembled within theapparatus of the invention. More particularly, the cabinet 16 is shownin cross-section with the work chamber 12 mounted on its upper surface14. The vacuum system communicates with the chamber 12 via a diffusionpump valve 91 and a line 92 which is provided for rough pumping of thechamber. A vent valve 93 is also provided for selectively comm unicatingthe chamber with atmospheric pressure or, in other words, venting thechamber.

The valve control arrangement includes spring means for normallymaintaining the valves 91 and 93 open and closed, respectively. Moreparticularly, the vent valve 93 is spring loaded by a compression spring94 to the closed position shown, and the diffusion pump valve 91 ismounted on a lever 96 which is spring loaded upward by a compressionspring 97 to maintain the diffusion pump valve in the open position. Asis illustrated, the lever 96 is pivoted on a support 98 which isintermediate its ends.

Each of the valves 91 and 93 are also provided with a drive rod 99 and101, respectively for actuating the same against the pressure of thespring means. That is, the drive rod 99 associated with the diffusionpump valve extends upwardly from within the cabinet 16 through amechanical vacuum gland 103 to a location at which its upper end isengagable with the free end of the valve lever 96. The drive rod 101associated with the vent valve extends downwardly from such valve toterminate within the housing 16.

It will be seen that with this arrangement both of the drive rods 99 and101 are axially translatable in the upward direction to overcome thepressure of the springs associated with their respective valves toactuate the same. That is, upward movement of the drive rod 99 willcompress the spring 97 to close the valve plate 91 over the valveopening leading to the diffusion pump 104. Upward axial translation ofthe drive rod 101 will likewise compress the compression spring 94associated with the valve 93 to lift the valve disc of 93 from theopening leading to the atmospheric pressure within the cabinet 16.

An activating lever 106 is provided for engaging the lower free ends ofboth of the drive rods 99 and 101 to axially translate the same tooperate their respective valves. As a particularly salient feature ofthe instant invention, the lever 106 is so designed and mounted withrespect to the remainder of the control apparatus that it assures thatthe diffusion pump valve is fully closed prior to such lever opening thevalve 93 to vent the chamber 12 to the atmosphere. That is, the lever106 is positioned adjacent to free ends of both of the rods and ispivotally mounted at one of its ends in a pivot structure 107 whichprovides a resilient pivot point for the lever. That is, a pin on thefree end of the lever is positioned between two compression springs 108which normally define the pivot point. It will be appreciated however,that such pivot point is releasable or movable against the pressure ofeither of such springs.

The actuating lever is so positioned and pivotally mounted with respectto the free endsof the drive rods 99 and 101 that upon being pivotedupward into the vent position, such lever will first engage the rod 99and translate the same upward to the extent necessary to close the valve91 over the diffusion pump prior to engaging the rod 101 associated withthe vent valve 93. This assures that the diffusion pump is not broughtup to atmospheric pressure.

It will be appreciated that if the activating lever 106 were fixedlypivoted within the cabinet 16, once the valve 91 is closed over thediffusion pump valve opening, further upward movement of the activatinglever would be prevented by the rod 99. However, the pivot pointprovided by the spring loaded pivot mounting 107 will be overridden byany force tending to move the lever 106 further upward with result thatthe free end of the rod 99 will become the pivot point for the lever.The lever can thus be continued to be moved upward to engage the rod 101and open the vent valve. Conventional catchmeans (not shown) can beprovided for maintaining the lever 106 in the vent position.

The vacuum system of the invention also includes sensing means fordetermining the position of the diffusion pump valves and the activatinglever 106 and utilizing such sensing to control a roughing valve 109 anda finishing or fore pump valve 111 to selectively communicate amechanical pump 112 with either the chamber 12 for rough pumping thechamber or the diffusion pump for pumping the latter. More particularly,a pair of microswitches 113 and 114 are located at positions at whichthey will be respectively contacted by the valve lever 96 and activatinglever 106 in preselected positions thereof. To facilitate anunderstanding of such valve control arrangement, it will be described interms of its operation. When the activating lever 106 is in the ventposition, the microswitch 114 will sense the same and close the roughingvalve while at the same time open the fore pump valve if the diffusionpump is on. Upon the lever being brought to the vacuum position, themicroswitch 114 will close the fore pump valve and open the roughingvalve so that the mechanical pump 112 can rough pump the chamber 12. Itwill be appreciated that the diffusion pump valve 91 will remain closedat this time until the pressure within chamber 12 is reduced to such apoint at which the pressure on the valve plate 91 will be insufficientto overcome the compression of spring 97. The force of spring 97 ischosen to not cause opening of the diffusion pump valve until thepressure within chamber 12 has been reduced by the mechanical pump 112to such a degree that the diffusion pump can effectively operate. Uponthe valve 91 being opened at such time, the microswitch 113 will sensethe opening and close the roughing valve while also opening the forepump valve so that the mechanical pump is communicated with thediffusion pump to provide for pumping of the same.

It can be seen from the above that even though only one control, lever106, need be operated by a user of the apparatus, the valve controlarrangement of the invention provides all actuations that are necessaryto assure failsafe operation. Moreover, it enables one mechanical pump,pump 112, to serve two functions. This facilitates making the vacuumsystem a compact arrangement which can be included within the cabinet16.

The electron beam generating apparatus of the invention also includesmeans for determining in a quite simple manner whether or not differentcomponents of the arrangement are functioning correctly. Moreparticularly, with reference to FIG. 9, a simple testing circuit isillustrated for determining whether or not, for example, the variouscomponents of the power supply are functioning correctly. To this end,each of the components which is to be tested is placed in electricalcommunication via a pair of leads 121 and 122 of the testing system witha voltage sensing means 123 which can be in the form of an adjustableresistor. The testing system further includes visual indicating means inthe form of a voltage registering meter 124, for example, for measuringthe voltage sensed by each of the resistors 123. Switching means 126 arealso provided for se lectively connecting each one of the individualresistors 123 with the indicating means to provide a reading on themeter representative of the functioning of the component associated withthe resistor so electrically connected with the meter. For example, onepair of the leads 121 and 122 can be connected across the 300 voltstorage capacitor of the power supply and a reading obtained on themeter 124 indicative of whether or not such capacitor truly has 300volts across it. Another one of the pair of leads 121 and 122 can beconnected across the microswitch 113 of the vacuum system to indicate onthe meter 124 whether or not the diffusion pump valve 91 is open or notopen as the case may be.

While the apparatus of the invention has been described with respect toa preferred embodiment, it will be appreciated by those skilled in theart that various changes and modifications are possible. For example,although all of the features described above cooperate to provide incombination an improved apparatus for generating an electron beam whichis especially adaptable for portable electron beam welding and the like,various ones of the features can find use independently of the others.In this connection, the particular arrangement described formanipulating the electron gun is also applicable to other systems whichmay or may not be portable. Mooreover, the gun chamber which includesthis manipulating means can be made separatable from environments. Inlight of this and other potential modifications, it is intended that thecoverage afforded applicant be limited only by the claims.

We claim:

1. Apparatus for directing impingement of a electron beam onto an objectto be irradiated thereby, comprising a chamber having a wall fordefining an evacuated volume adjoining the portion of said object to beirradiated; means mounted within said chamber on a first movable portionof the chamber wall for generating said electron beam; and positioningmeans for varying the angle of the path of said beam with respect tosaid object, said positioning means including connecting meanshermetically securing said first portion of said wall to the remainderof the chamber wall in a manner enabling angular reorientation of saidfirst portion of said wall with respect to the remainder of said wall; ahandle secured to said first portion of said wall exteriorly of saidchamber for grasping by an operator for pivotal manipulation to providesaid angular reorientation of said first wall portion and toconsequently pivot said beam introducing means to change the angle atwhich said beam is introduced into said chamber; locking means forselectively locking said first portion of said chamber wall in a desiredangular orientation with respect to the remainder of said wall tothereby enable selective locking of said electron beam generating meansin a desired orientation for maintaining an electron beam issuingtherefrom at a desired angle with respect to said object; a high vacuumsystem for evacuating said chamber to a vacuum enabling the formation ofsaid electron beam; an electrical power supply for producing the highvoltage necessary for operation of said electron beam generating means;and a high voltage electrical lead extending hermetically through thewall of said chamber for connecting said electron beam generating meansto said power supply.

2. The apparatus of claim 1 wherein a support plate is provided withinsaid chamber for supporting an object to be irradiated, and means areprovided for applying a positive electrical bias to said plate forcapturing stray electrons within said chamber.

3. The apparatus of claim 1 wherein said connecting means is a flexiblesecond wall portion of said chamber secured between said first wallportion and the remainder of the chamber wall.

4. The apparatus of claim 3 wherein said second wall portion of saidchamber is a generally cylindrical flexible bellows interposed betweensaid first wall portion and the remainder of the chamber wall.

5. The apparatus of claim 4 wherein said locking means includes a pairof gimbally mounted rings surrounding said bellows and connected betweensaid first wall portion and the remainder of the chamber wall, and alock for maintaining said rings and hence said bellows in apredetermined orientation.

6. The apparatus of claim 1 wherein said means for generating saidelectron beam is an electron gun; and means are provided for removablymounting said gun within said chamber on said first wall portion, saidmeans comprising a socket associated with said first wall portion ofsaid chamber for receiving an end portion of the body of said electrongun, cooperating means on said gun and at said socket for removablysecuring said end portion of said gun within said socket with amechanical snap fit, and cooperating electrical connectors on said gunand at said socket for providing connection between electrical elementsof said gun and said socket when said gun end portion is mechanicallysecured within said socket.

7. The apparatus of claim 6 wherein said electron gun includes agenerally U-shaped filament for emitting electrons which is mounted atspaced locations on a support via its two legs, an anode mountedadjacent the base of said U-shaped wire filament for drawing electronstherefrom, and focusing means for defining an electron beam with saidelectrons, said filament including a third leg secured between said baseof said filament and a location on said support which is to the side ofthe locations at which the legs of said U-shaped portion thereof aresecured, whereby a tripod support is provided for said filament toenable the same to maintain its structural integrity at extended highoperating temperatures.

8. The apparatus of claim 6 wherein a power supply for said electron gunis provided as a part of said combination and includes rectifying meansfor converting alternating line current to direct current andtransformer means for converting the voltage of said line current to asubstantially higher voltage, and wherein a support plate is providedwithin said chamber for supporting an object to be irradiated, and meansare provided for applying a positive electrical bias to said plate forcapturing stray electrons within said chamber.

9. The apparatus of claim 8 wherein testing means are provided forelectrically determining whether or not different components of saidapparatus are functioning correctly, said testing means including aplurality of voltage sensing means, each one of which is in electricalcommunication with a respective one of said components to be tested,indicating means for registering a sensed voltage, and switching meansfor electrically connecting said indicating means individually with eachof said voltage sensing means to provide indications representative ofthe functioning of the component associated with the voltage sensingmeans electrically connected with said indicating means.

10. The apparatus of claim 9 wherein a pair of valves are provided forselectively communicating said chamber with atmospheric pressure andwith a diffusion pump of said vacuum system; and actuating means forsaid valves are provided which comprise means for normally maintainingthe diffusion pump valve in an open position while maintaining theatmospheric pressure valve in a closed position, first and secondgenerally parallel drive rods respectively associated with saiddiffusion pump valve and said atmospheric pressure valve, both of whichrods are axially translatable to actuated positions respectively closingsaid diffusion pump valve and opening said atmospheric pressure valve,an activating lever positioned adjacent the free ends of both of saidrods for engagement therewith to provide said axial translation, meanspivotally mounting said lever at a position relative to said free endswhereby upon being pivoted said lever engages the rod associated withsaid diffusion pump valve and axially translates the same to its fullyactuated position to close said valve before engaging the rod associatedwith said atmospheric pressure valve, said pivot means being releasableto enable the free end of the rod associated with said diffusion pumpvalve to become the pivot point of said lever for continued movement ofsaid lever in the same direction for engagement with the free end of therod associated with said atmospheric pressure valve rod to translate thelatter rod to its fully activated position, whereby the closing of saiddiffusion pump valve is completed prior to the opening of saidatmospheric pressure valve.

11. Apparatus for directing impingement of an electron beam onto anobject comprising a chamber for defining an evacuated volume; anelectron gun for generating an electron beam; and means for removablysecuring said electron gun with said chamber comprising a socketassociated with a wall portion of said chamber for receiving an endportion of the body of said electron gun, cooperating means on said gunand at said socket for removably securing said end portion of said gunwithin said socket with a mechanical snap fit, and cooperatingelectrical connectors on said gun and at said socket for providingconnection between the electrical elements of said gun and said socketwhen said gun end portion is mechanically secured within said socket,said cooperating means on said gun and at said socket for removablysecuring said end portion of said gun within said socket with amechanical snap fit including an indentation on one of said end portionsof said gun and said socket and a protuberance adapted to mate with saidindentation of the other of said end portion of said gun and saidsocket, and one of said protuberance and the means defining theindentation being resiliently mounted on its associated member to enablemovement thereof against said resiliency to permit mating of saidprotuberance with said deformation.

12. The apparatus of claim 11 in which said indentation is acircumferential groove on the inner surface of said socket and saidprotuberance is provided by an annularly arrayed plurality of leafspring fingers projecting axially of said gun and being deformedradially outwardly of said gun to provide in the aggregate acircumferential protuberance for mating with said groove within saidsocket.

13. Apparatus for generating an electron beam for impingement onto anobject comprising a generally U- shaped wire filament for emittingelectrons, which filament is mounted via its two legs at spacedlocations on a support; an anode mounted adjacent the base of saidU-shaped wire filament for drawing electrons from said base; andfocusing means for defining an electron beam with said electrons, saidfilament including a third leg secured between said base of saidfilament and a location on said support which is to the side of thespaced locations thereon at'which the legs of said U-shaped portion ofsaid filament are secured, whereby a tripod support is provided for saidfilament to enable the same to maintain its structural integrity atextended high operating temperatures.

14. The apparatus of claim 13 wherein said third leg is a wire leg andis secured to said base of said U-shaped wire filament by being wrappedtherearound to also provide said filament with an enlarged electronemitting surface.

15. Apparatus for directing the impingement of a beam of radiation ontoan object comprising a chamber for defining an evacuated volumeadjoining the portion of the object to be irradiated; means forgenerating the desired beam of radiation in said evacuated volume; apower supply for powering said beam generating means; and testing meansfor electrically determining whether or not selected differentcomponents of said apparatus are functioning correctly, said testingmeans including as parts of said apparatus a plurality of voltagesensing means, each one of which is in electrical communication with arespective one of said components to be tested, indicating means as partof said apparatus for visually registering a sensed voltage, andmanually operable switching means on said apparatus for electricallyconnecting said indicating means individually with each of said voltagesensing means to provide indications visually representative of thefunctioning of the component associated with the voltage sensing meanselectrically connected with said indicating means.

16. Apparatus for activating a pair of valves of a high vacuum systemcomprising means for normally maintaining a first one of said valves inan open position and the second one thereof in a closed position; firstand second generally parallel drive rods respectively associated withsaid first and second valves, both of said rods being axiallytranslatable in the same direction to actuated positions respectivelyclosing said first valve and opening said second valve; an activatinglever positioned adjacent the free ends of both of said rods forengagement therewith to provide said axial translation; and meanspivotally mounting said lever at a position relative to said free endsat which upon being pivoted said lever engages one of said rods andaxially translates the same to its fully actuated position beforeengaging the other, said one of said rods being prevented fromsubstantially any further axial translation in said direction uponreaching said fully actuated position, and said pivot means beingreleasable to enable the free end of the engaged rod to become the pivotpoint of said lever for continued movement of said lever in the samedirection for engagement with the free end of the other one of said rodsto translate the latter rod to its fully actuated position, whereby theactuation of one of said valves by said lever is completed prior to theactuation of the other.

1. Apparatus for directing impingement of a electron beAm onto an objectto be irradiated thereby, comprising a chamber having a wall fordefining an evacuated volume adjoining the portion of said object to beirradiated; means mounted within said chamber on a first movable portionof the chamber wall for generating said electron beam; and positioningmeans for varying the angle of the path of said beam with respect tosaid object, said positioning means including connecting meanshermetically securing said first portion of said wall to the remainderof the chamber wall in a manner enabling angular reorientation of saidfirst portion of said wall with respect to the remainder of said wall; ahandle secured to said first portion of said wall exteriorly of saidchamber for grasping by an operator for pivotal manipulation to providesaid angular reorientation of said first wall portion and toconsequently pivot said beam introducing means to change the angle atwhich said beam is introduced into said chamber; locking means forselectively locking said first portion of said chamber wall in a desiredangular orientation with respect to the remainder of said wall tothereby enable selective locking of said electron beam generating meansin a desired orientation for maintaining an electron beam issuingtherefrom at a desired angle with respect to said object; a high vacuumsystem for evacuating said chamber to a vacuum enabling the formation ofsaid electron beam; an electrical power supply for producing the highvoltage necessary for operation of said electron beam generating means;and a high voltage electrical lead extending hermetically through thewall of said chamber for connecting said electron beam generating meansto said power supply.
 2. The apparatus of claim 1 wherein a supportplate is provided within said chamber for supporting an object to beirradiated, and means are provided for applying a positive electricalbias to said plate for capturing stray electrons within said chamber. 3.The apparatus of claim 1 wherein said connecting means is a flexiblesecond wall portion of said chamber secured between said first wallportion and the remainder of the chamber wall.
 4. The apparatus of claim3 wherein said second wall portion of said chamber is a generallycylindrical flexible bellows interposed between said first wall portionand the remainder of the chamber wall.
 5. The apparatus of claim 4wherein said locking means includes a pair of gimbally mounted ringssurrounding said bellows and connected between said first wall portionand the remainder of the chamber wall, and a lock for maintaining saidrings and hence said bellows in a predetermined orientation.
 6. Theapparatus of claim 1 wherein said means for generating said electronbeam is an electron gun; and means are provided for removably mountingsaid gun within said chamber on said first wall portion, said meanscomprising a socket associated with said first wall portion of saidchamber for receiving an end portion of the body of said electron gun,cooperating means on said gun and at said socket for removably securingsaid end portion of said gun within said socket with a mechanical snapfit, and cooperating electrical connectors on said gun and at saidsocket for providing connection between electrical elements of said gunand said socket when said gun end portion is mechanically secured withinsaid socket.
 7. The apparatus of claim 6 wherein said electron gunincludes a generally U-shaped filament for emitting electrons which ismounted at spaced locations on a support via its two legs, an anodemounted adjacent the base of said U-shaped wire filament for drawingelectrons therefrom, and focusing means for defining an electron beamwith said electrons, said filament including a third leg secured betweensaid base of said filament and a location on said support which is tothe side of the locations at which the legs of said U-shaped portionthereof are secured, whereby a tripod support is provided for saidfilament to enable the same to maiNtain its structural integrity atextended high operating temperatures.
 8. The apparatus of claim 6wherein a power supply for said electron gun is provided as a part ofsaid combination and includes rectifying means for convertingalternating line current to direct current and transformer means forconverting the voltage of said line current to a substantially highervoltage, and wherein a support plate is provided within said chamber forsupporting an object to be irradiated, and means are provided forapplying a positive electrical bias to said plate for capturing strayelectrons within said chamber.
 9. The apparatus of claim 8 whereintesting means are provided for electrically determining whether or notdifferent components of said apparatus are functioning correctly, saidtesting means including a plurality of voltage sensing means, each oneof which is in electrical communication with a respective one of saidcomponents to be tested, indicating means for registering a sensedvoltage, and switching means for electrically connecting said indicatingmeans individually with each of said voltage sensing means to provideindications representative of the functioning of the componentassociated with the voltage sensing means electrically connected withsaid indicating means.
 10. The apparatus of claim 9 wherein a pair ofvalves are provided for selectively communicating said chamber withatmospheric pressure and with a diffusion pump of said vacuum system;and actuating means for said valves are provided which comprise meansfor normally maintaining the diffusion pump valve in an open positionwhile maintaining the atmospheric pressure valve in a closed position,first and second generally parallel drive rods respectively associatedwith said diffusion pump valve and said atmospheric pressure valve, bothof which rods are axially translatable to actuated positionsrespectively closing said diffusion pump valve and opening saidatmospheric pressure valve, an activating lever positioned adjacent thefree ends of both of said rods for engagement therewith to provide saidaxial translation, means pivotally mounting said lever at a positionrelative to said free ends whereby upon being pivoted said lever engagesthe rod associated with said diffusion pump valve and axially translatesthe same to its fully actuated position to close said valve beforeengaging the rod associated with said atmospheric pressure valve, saidpivot means being releasable to enable the free end of the rodassociated with said diffusion pump valve to become the pivot point ofsaid lever for continued movement of said lever in the same directionfor engagement with the free end of the rod associated with saidatmospheric pressure valve rod to translate the latter rod to its fullyactivated position, whereby the closing of said diffusion pump valve iscompleted prior to the opening of said atmospheric pressure valve. 11.Apparatus for directing impingement of an electron beam onto an objectcomprising a chamber for defining an evacuated volume; an electron gunfor generating an electron beam; and means for removably securing saidelectron gun with said chamber comprising a socket associated with awall portion of said chamber for receiving an end portion of the body ofsaid electron gun, cooperating means on said gun and at said socket forremovably securing said end portion of said gun within said socket witha mechanical snap fit, and cooperating electrical connectors on said gunand at said socket for providing connection between the electricalelements of said gun and said socket when said gun end portion ismechanically secured within said socket, said cooperating means on saidgun and at said socket for removably securing said end portion of saidgun within said socket with a mechanical snap fit including anindentation on one of said end portions of said gun and said socket anda protuberance adapted to mate with said indentation of the other ofsaid end portion of said gun and said socket, and One of saidprotuberance and the means defining the indentation being resilientlymounted on its associated member to enable movement thereof against saidresiliency to permit mating of said protuberance with said deformation.12. The apparatus of claim 11 in which said indentation is acircumferential groove on the inner surface of said socket and saidprotuberance is provided by an annularly arrayed plurality of leafspring fingers projecting axially of said gun and being deformedradially outwardly of said gun to provide in the aggregate acircumferential protuberance for mating with said groove within saidsocket.
 13. Apparatus for generating an electron beam for impingementonto an object comprising a generally U-shaped wire filament foremitting electrons, which filament is mounted via its two legs at spacedlocations on a support; an anode mounted adjacent the base of saidU-shaped wire filament for drawing electrons from said base; andfocusing means for defining an electron beam with said electrons, saidfilament including a third leg secured between said base of saidfilament and a location on said support which is to the side of thespaced locations thereon at which the legs of said U-shaped portion ofsaid filament are secured, whereby a tripod support is provided for saidfilament to enable the same to maintain its structural integrity atextended high operating temperatures.
 14. The apparatus of claim 13wherein said third leg is a wire leg and is secured to said base of saidU-shaped wire filament by being wrapped therearound to also provide saidfilament with an enlarged electron emitting surface.
 15. Apparatus fordirecting the impingement of a beam of radiation onto an objectcomprising a chamber for defining an evacuated volume adjoining theportion of the object to be irradiated; means for generating the desiredbeam of radiation in said evacuated volume; a power supply for poweringsaid beam generating means; and testing means for electricallydetermining whether or not selected different components of saidapparatus are functioning correctly, said testing means including asparts of said apparatus a plurality of voltage sensing means, each oneof which is in electrical communication with a respective one of saidcomponents to be tested, indicating means as part of said apparatus forvisually registering a sensed voltage, and manually operable switchingmeans on said apparatus for electrically connecting said indicatingmeans individually with each of said voltage sensing means to provideindications visually representative of the functioning of the componentassociated with the voltage sensing means electrically connected withsaid indicating means.
 16. Apparatus for activating a pair of valves ofa high vacuum system comprising means for normally maintaining a firstone of said valves in an open position and the second one thereof in aclosed position; first and second generally parallel drive rodsrespectively associated with said first and second valves, both of saidrods being axially translatable in the same direction to actuatedpositions respectively closing said first valve and opening said secondvalve; an activating lever positioned adjacent the free ends of both ofsaid rods for engagement therewith to provide said axial translation;and means pivotally mounting said lever at a position relative to saidfree ends at which upon being pivoted said lever engages one of saidrods and axially translates the same to its fully actuated positionbefore engaging the other, said one of said rods being prevented fromsubstantially any further axial translation in said direction uponreaching said fully actuated position, and said pivot means beingreleasable to enable the free end of the engaged rod to become the pivotpoint of said lever for continued movement of said lever in the samedirection for engagement with the free end of the other one of said rodsto translate the latter rod to its fully actuated position, wherebY theactuation of one of said valves by said lever is completed prior to theactuation of the other.